Modular sand filtration—anchor system and wave energy water desalination system incorporating the same

ABSTRACT

A potable water producing system for disposition at a body of salt water and a method of producing potable water is provided. The system includes a wave energy conversion system (AWECS) and a portable filtration-anchor system. The AWECS is in the form of a floating articulated barge housing a desalination system including a reverse osmosis membrane. The filtration-anchor system is submerged in the body of salt water and includes a sand filter to filter the adjacent salt water and to provide the filtered salt water to the desalination system on the articulated barge. The action of the waves on the articulated barge provides energy to pump the filtered salt water from the sand filter to the reverse osmosis member to produce potable water. Moreover, the action of the waves on the articulated barge effects the shaking of the reverse osmosis filter, thereby rendering it self-cleaning.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation-In-Part application that claims thebenefit under 35 U.S.C. §120 of U.S. patent application Ser. No.13/929,171, filed on Jun. 27, 2013, entitled Modular SandFiltration-Anchor System, which in turn is a non-provisional applicationand claims the benefit under 35 U.S.C. §119(e) of Application Ser. No.61/668,213 filed on Jul. 5, 2012 also entitled Modular SandFiltration-Anchor System and all of whose entire disclosures areincorporated by reference herein.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

“Not Applicable”

SPECIFICATION Background of the Invention

The present invention is generally directed to the generation of potablewater. More particularly, the present invention is directed toarticulated wave energy conversion system (AWECS) with reverse osmosis(RO) membranes to generate potable water.

Desalinization plants are located around the world, and are operatedusing electricity to pressurize the incoming source water. Depending onthe location, there may be pretreatment requirements to optimize theinfluent for processing through the RO membranes.

The U.S. Department of Interior (DOI) funded the Subfloor Water IntakeStructure System (SWISS), currently utilized in desalination plants inCalifornia and Japan. The SWISS approach is to install a permanentsubfloor well/intake system for the source-water for the traditionalshore structures. The in-situ sand provides the filtration media. See,for example, Lovo, Robert, “Initial Evaluation of the Subfloor WaterIntake Structure System (SWISS) vs. Conventional Multimedia PretreatmentTechniques,” Assistance Agreement No. 98-FC-81-0044, DesalinationResearch and Development Program Report No. 66, U.S. Dept. of Interior,May 2001.

Ocean wave-energy conversion is directed to the exploitation of oceanwave energy to produce energy in one or more of four forms, those beinghydraulic, pneumatic, mechanical or electrical. See McCormick, “OceanWave Energy Conversion,” published by Wiley-Interscience, New York(1981, reprinted by Dover Publication, Long Island, N.Y. in 2007). Thearticulated-barge wave-energy conversion system dates back to the 1970'swhen both Sir Christopher in the United Kingdom and Glen Hagen of theUnited States suggested the system. The system was studied in the late1970's by P. Haren (1978) at MIT. He found that the optimumarticulated-barge configuration was a three-barge system. In the 1980's,Dr. Peter McCabe showed that the efficiency of the three-barge systemcould be substantially improved by suspending an inertial-damping platebelow the center barge. Dr. McCabe, then, produced a prototype of thesystem, coined the McCabe Wave Pump (MWP), which was deployed andstudied in the Shannon Estuary for approximately nine years. See, U.S.Pat. No. 5,132,550 (McCabe). The MWP was primarily designed as aproducer of potable water.

Ocean Energy Systems (OES) is in the business of designing andmanufacturing articulated-barge systems to produce potable water byreverse-osmosis (RO) desalination of sea water. U.S. Patent PublicationNo. 2009/0084296 (McCormick), which is incorporated by reference herein,describes a system directed to a wave-powered device having enhancedmotion. In particular, there is disclosed an articulated barge waveenergy converter system, which shall hereinafter be referred to as theAWECS. See also U.S. Patent Publication No. 2010/0320759 (Lightfoot, etal.). The AWECS basically comprises a forward barge, a rear barge and anintermediate or center barge, all of which arranged to float on a bodyof water having waves. The barges are hingedly coupled together so thatthey can articulate with respect to each other in response to wavemotion. The AWECS also includes high-pressure pumps which straddle andpivotably connect the barge-pairs, e.g., at least one pump connects theforward barge and the intermediate barge, and at least another pumpconnects the rear barge and the intermediate barge. The pumps aredesigned to draw in the water through a pre-filter, pressurize thewater, and deliver the water to an on-board reverse osmosis (RO)desalination system. That system includes an RO membrane. As an incomingwave makes contact with the forward barge first, the hydraulic fluid inthe pump(s) coupled between the forward barge and the center barge aredriven in a first direction; as the wave continues, the hydraulic fluidin the pump(s) coupled between the rear barge and the center barge aredriven in a second opposite direction. The end results arebi-directional hydraulic pumps.

In U.S. Provisional Patent Application Ser. No. 61/707,206, filed onSep. 28, 2012, there is disclosed an AWECS arranged for producingelectrical energy from the wave energy. To that end it makes use of anAWECS similar to that described above, except that it can make use of acommercially-available rotary-vane pump to drive a generator to producethe electricity. To that end, the invention of that ProvisionalApplication entails a floating device having a first portion (e.g., afirst barge) movably coupled (e.g., hinged) to a second portion (e.g., asecond barge); at least one hydraulic or pneumatic pump (e.g., a linearpump) coupled between the first portion the said second portion, thehydraulic pump driving a hydraulic fluid therein when the first portionmoves with respect to the second portion due to wave energy. A fluidrectifier is provided in the AWECS and is in fluid communication withthe at least one hydraulic or pneumatic pump, that generates aunidirectional hydraulic or pneumatic fluid flow. A rotary vane pump iscoupled to the fluid rectifier. The rotary vane pump uses theunidirectional flow to generate a rotational motion via a drive member.A rotating electrical generator (e.g., a DC generator) is coupled tothat drive member, so that the drive member causes the rotatingelectrical generator to generate electricity when the drive member isrotating.

All references cited herein are incorporated herein by reference intheir entireties.

BRIEF SUMMARY OF THE INVENTION

In accordance with one aspect of this invention a system for producingpotable water is provided. The system basically comprises anarticulating barge system and at least one filter-anchor. Thearticulated barge system is arranged for floating on a body of saltwater having waves and includes a desalination system to produce potablewater from filtered salt water. The barge system is arranged forconverting energy of the waves into energy to pump the filtered saltwater to the desalination system. The desalination system includes areverse osmosis membrane, which is arranged to be self-cleaned by theaction of the waves on the barge system. The at least one filter-anchoris arranged for placement on the floor of the body of salt water andcomprises a filter housing and a filter. The filter housing has aninterior chamber, at least one inlet, at least one outlet, and a filter,e.g., a sand filter, located within the filter housing. The at least oneinlet is arranged for providing salt water to the filter. The filter isadapted to filter the salt water to produce filtered salt water. Theoutlet of the at least one filter-anchor is coupled to the desalinationsystem, whereupon the salt water can be drawn into the filter andfiltered to produce filtered water which can be pumped from the outletto the desalination system by the energy of the waves.

In accordance with another aspect of this invention a method forproducing potable water is provided. The method entails floating anarticulated barge system on a body of salt water having waves. The bargesystem includes a desalination system to produce potable water fromfiltered salt water. The desalination system includes a reverse osmosismembrane. At least one filter-anchor is disposed on the floor of thebody of salt water. The filter-anchor comprises a filter housing and afilter. The filter housing has an interior chamber, at least one inlet,at least one outlet, and a filter located within the filter housing. Theat least one inlet is arranged for providing salt water to the filter.The filter is adapted to filter the salt water to produce filtered saltwater. The method also entails coupling the outlet of the filter-anchorto the desalination system on the barge system and using the bargesystem to convert the energy of the waves into energy to pump thefiltered salt water to the desalination system, whereupon the filteredsalt water is converted to potable water utilizing the reverse osmosismembrane. The reverse osmosis membrane is self-cleaned by the action ofthe waves on the barge system.

In accordance with one preferred aspect of this invention the inlets forproviding sea water to the filter-anchor may provide for a surfaceintake velocity of less than 0.5 feet per second to restrict incursionof fish larva and macro or micro vertebrae. The filter-anchor may be ofa size to permit container transportable via truck transportation. Theinterior chamber of the filter anchor may be substantially filled withclean, washed, coarse sand, from either a local beach or shorelinesource or from sand obtained from a commercial sand source. The filterhousing may have hatches between the exterior and the interior chamberwhich, when opened, provide for submersion of the filter housing viaflooding of the interior chamber and controlled sinking of thefilter-anchor to the floor of the body of salt water. The filter-anchor,prior to use as a filter, may be floatable and towable to a deploymentsite in the body of salt water. The filter-anchors may be provided withassociated (respective) mooring buoys, which are preferably attached tothe filter-anchors by a mooring line. At least one submersible pump andsubmersible air snorkel may be included such that the filter-anchor isre-floatable when the hatches are in a closed position, wherein theinterior chamber is substantially filled with air, wherein thesubmersible pump and air snorkel are activatable to float thefilter-anchor.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

The invention will be described in conjunction with the followingdrawings in which like reference numerals designate like elements andwherein:

FIG. 1 is a simplified schematic diagram of an articulated wave energyconversion system and a modular sand filtration-anchoring system inaccordance with an exemplary embodiment of the present invention;

FIG. 2 is an isometric view of the modular sand filtration-anchoringsystem of FIG. 1;

FIG. 3 is a front cross-section view of the modular sandfiltration-anchoring system of FIG. 1;

FIG. 4 is a side elevation view of the modular sand filtration-anchoringsystem of FIG. 1;

FIG. 5 is a top, plan view of the modular sand filtration-anchoringsystem of FIG. 1; and

FIG. 6 is a functional diagram of an AWECS pump depicting how a highpressure flow of filter sea water is generated by wave motion of thebarges for provision to a RO membrane in the barges to produce potablewater thereat.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawing wherein like characters refer to likeparts, there is shown in FIG. 1 a system for producing potable waterfrom salt water in a body of water, e.g., a sea, having waves. Thesystem basically comprises an AWECS and a portable filtration-anchorsystem. The AWECS is a system in the form of articulated barge andincludes a desalination system. The desalination system is constructedsimilarly to the AWECS described above, e.g., it includes a forwardbarge 12A, a rear barge 12B and an intermediate or center barge 12C. Thebarges are hinged to each other and include at least one pump 13Astraddling the forward barge 12A and center barge 12C and at least onepump 13B straddling the rear barge 12B and center barge 12C. A reverseosmosis membrane 15 is disposed in one of the barges and is arranged toprocess filtered salt water provided from the portable filtration-anchorsystem to produce potable water. The portable filtration-anchor systemis arranged for disposition on the floor or bed of the body of saltwater to filter the salt water which is brought into it and to providethe filtered salt water to the desalination system on the articulatedbarge system. Power for drawing the salt water from the body of waterinto the filter-anchor, where it is filtered into filtered salt water,and for providing the filtered saltwater to the desalination system onthe articulated barge system is accomplished by the action of the wavesof the body of water on the barge system. In particular, as will bediscussed in detail later the AWECS includes pumps which are powered bythe energy extracted from the action of the waves on the barge system.

The system for producing potable water will be illustrated in moredetail with reference to the following embodiments, but it should beunderstood that the present invention is not deemed to be limitedthereto. To that end, one exemplary embodiment of an AWECS 10constructed in accordance with an exemplary embodiment of the presentinvention is shown in FIG. 1 and includes the three previouslyidentified articulated barges 12A, 12B and 12C. The barges are anchoredusing, for example, a 3-point anchoring system utilizing mooring buoys14, 16, 18 having filter-anchor units 20, 22, 24. The filter-anchorunits 20, 22, 24 form one exemplary embodiment of the portablefiltration-anchor system and serve as intakes for the articulatedbarges, allowing seawater to be pre-filtered prior to enteringdesignated barges, with negligible effects on aquatic life. This systemis, for example, a containerized version of the SWISS (as discussed inthe Background, above).

The seawater will be pressurized and processed through an onboardreverse osmosis system. The onboard reverse osmosis system can be of anysuitable construction and includes a conventional reverse osmosis (RO)membrane 15. The reverse osmosis system operates in a conventionalmanner to produce potable water from salt water exposed to the ROmembrane. However, the fact that the RO membrane is located in thearticulated barge system renders it self-cleaning. In this regard, sincethe barge system is floating on the body of salt water where it isexposed to the rocking action of the waves (an exemplary direction ofthe wave flow is shown by the arrow in FIG. 1), this rocking actioneffectively shakes or otherwise disturbs the RO membrane to effectivelyclean it. Thus, the RO membrane is effectively self-cleaning.

For the design sea (for example, a 1.5-meter significant wave height and7-second period), the exemplary potable water producing system of thisinvention shown in FIG. 1 and described further below can produce anaverage of 100,000 gallons per day (gpd) of potable water. This value isbased on 200,000 gpd of source water taken in through the sandfiltration system. However, it is intended that the AWECS 10 willoperate in greater and lesser seas, wherein the potable-water productionwill vary with the sea conditions.

The filter-anchor units 20, 22, 24 are preferably built to betransportable via over-the-road trucking (as are all of the AWECScomponents).

As can be seen in FIGS. 3 and 5, and which will be described later, thesmall barge-like filter-anchors 20, 22, 24 include respective interiorchambers 48, which are preferably lined with a porous fabric, such as awoven geotextile bag 26 (e.g., a Geotube® brand permeable fabric) filledwith sand 28. The permeability of the geotextile is in gallons persquare feet. It will not be the restricting permeability of the system.As an alternative to a bag 26, a porous cover, formed of the samematerial as the bag 26, may be provided over the body of sand within thechamber 48 to hold the sand in place within the chamber.

The sand 28 to be used in the filter-anchors 20, 22, 24 is preferablycoarse washed sand placed into the geotextile bag 26. The estimatedcoefficient of permeability (K) of the sand is expected to be between0.003 and 0.00003 ft/s. Any combination of engineered sand and gravelmay be used to obtain best filtering results

It is anticipated that (for example) 200,000 gpd of supply water will bepulled through the three filter-anchors 20, 22, 24 in the presentexample. In this exemplary embodiment, the surface area for a singlefilter may be 30′×6′ or 180 square feet. For three such filter-anchors20, 22, 24, the surface area would be approximately 540 square feet. Ata rate of 0.003 fps, all three units would allow 1.62 cubic feet/secondor 12.1 gallons/second. This translates to 726 gallons per minute or1,045,440 gallons per day. Each modular filter-anchor 20, 22, 24 isestimated to handle approximately 348,480 gallons/day, depending on thesea state.

As stated above, the AWECS 10 is designed to be deployed (e.g., floated)in a body of salt water, e.g., sea having, for example, a 1.5-metersignificant wave height and seven-second period. However, the AWECS 10will operate in greater and lesser seas or bodies of salt water, and thepotable-water production will vary with the sea/salt water conditions.

As can be seen in FIGS. 2-5, each filter-anchor 20, 22, 24 is in theform of a modular filter housing 30 having an exterior 50 and aninterior chamber 48. The woven geotextile bag 26 with the sand 28therein is disposed within the interior chamber 48. The housing 50includes at least one inlet 52 for providing sea water to the interiorchamber 48, and at least one water conduction outlet conduit 38 forenabling the filtered water to exit (i.e., be pumped out) the interiorchamber 48.

The filter-anchor 20 includes at least one feed line 36 located in theinterior chamber 48 to provide the filtered water to the waterconduction outlet conduit 38. The feed lines 36 are perforated orotherwise allow for the salt water filtered by the sand that is inchamber 48 to enter the lines 36. The feed lines 36 can be V-line wellpiping. Only water that passes through the filter (e.g., the geotextilebag 26) may enter the feed lines 36.

The modular filter housing 30 may be constructed from steel sheet 32.The at least one inlet 52 may be in the form of apertures or openings inthe side of the filter housing 30 and may have manually or automaticallycontrolled hatches to control water flow therethrough.

Referring now to FIGS. 2-5 more details of the construction of themodular filter housing 30 will be provided. To that end, each housing 30is a barge-like structure that can be floated into place adjacent theAWECS. That is, the modular filter housing 30 will, first, be able tobarge the sand 28 in the geotextile bag 26 to the site where it will beused to make potable water. The sheet steel 32 will be used for theskin, for example, is approximately ⅜ inch thick. There will be variousbeam members 34 either I-beams or channel beams to provide structuralsupport for the housing. Moreover, the modular filter housing 30 willpreferably be protected from electrolysis using sacrificial zinc anodicprotection. It may also be painted to reduce the surface corrosion, asdetermined necessary. While the exemplary embodiment of the filterhousing 30 is shown and described as being formed of sheet steel, othermaterials can be used. For example, another possible material for thefilter housing 30 may be concrete.

The geotextile bag 26 may be, for example, polyethylene, woven fabric.Seam strength may be, for example, approximately 450 pounds per inchpull. The bag 26 (or a porous cover formed of the same material as thebag) serves to keep the sand 28 from washing from the submerged filterstructure.

The feed lines 36 may be constructed of, for example, high densitypolyethylene, and may be encased in filter fabric and stone sleeve toprevent sand 28 from being pulled into the feed lines 36.

The feed lines 36 serve to transport filtered salt water, e.g., seawater, through a manifold 37 to preferably, a single water conductionoutlet conduit 38 that is, for example, six inches in diameter. Thewater conduction conduit 38 penetrates the filter housing 30 and is thesource for water lines 60, 62, 64 (see FIG. 1) extending to the AWECSpumps. For example, two four-inch feed lines 36 connect to the six-inchwater conduction outlet conduit 38. The operation of the AWECS pumps 13Aand 13B pulls the filtered sea water from the chamber 48 to the reverseosmosis membrane 15 in the AWECS. The power for operating the pumps isprovided by the wave energy captured by the articulating barges 12A-12C.

As can be seen in schematically in FIG. 2, the filter housing 30 mayhave manually-operated scuttles or hatches at the inlets 52 in the sides44 of the housing to allow for flooding of the entire filter housing 30.The number of hatches will be sufficient to allow for a controlledsubmersion and re-flotation of the unit. The re-flotation will be doneby, first, attaching a snorkel (not shown) through the free-surface ofthe water and, then, using a submerged pump (not shown) to de-water thefilter system. Air is drawn in through the snorkel to replace the purgedwater in the bilge and gunnel areas of the modular filter-anchors 20,22, 24. The filter housing 30 may be capped and made water tight priorto re-float to allow removal of as much water as possible from this areato provide the additional buoyancy required for re-float.

A method of anchoring a wave energy conversion system 10 and providingfiltered water to the desalination system is also provided. The methodincludes the steps of towing an articulated barges for converting waveenergy into energy used to pump water to an RO membrane to generatepotable water to a location in an ocean, sea or other salt water bodyhaving waves, towing at least one filter-anchor 20, 22, 24 (as describedabove) to the same location and sinking each filter-anchor to the oceanbed. That action is accomplished by filling the interior chamber of thefilter housing with water. A mooring buoy 14, 16, 18 is provided foreach filter-anchor 20, 22, 24 at their respective locations. The mooringbuoys 14, 16, 18 are attached to respective ones of the filter-anchors20, 22, 24 by respective mooring lines 54, 56, 58. The filter-anchors20, 22, 24 are attached to the articulated barges 12. Source salt waterto the RO membrane is then provided from the filter-anchors via thewater lines 60, 62 and 64 by the operation of the AWECS pumps.

As mentioned earlier, the AWECS pumps 13A and 13B pull the filtered seawater from the chamber 48 to the reverse osmosis membrane 15. As shownmost clearly in FIG. 6, an AWECS pump (13A or 13B) comprises abi-directional linear pump 100 that is powered by the relative motionsof the barges 12A/12C or 12B/12C via movable couplings (e.g., hinges).As can be appreciated from FIG. 6, movement of a piston 102A within apiston chamber 102B as driven by a piston rod 102C whose other end (notshown) is coupled to either barge 12A or 12B, causes sea water from afilter-anchor unit to be moved in opposite linear directions. As aresult, a “flow rectifier” 200 is required to convert thisbi-directional sea water flow into a unidirectional fluid flow. Thisunidirectional sea water flow is then delivered to the reverse osmosismembrane 15. The housing 102B comprises pressure taps 104 that feed intocorresponding pressure tap pairs 204 in the flow rectifier 200 viacontrol pressure lines 106. Intake/Exhaust taps 108 are coupled viaintake/exhaust lines 110 respectively to rectifier passageways 205.Rectifier valve pairs 206A and 206B (e.g., cone-head valves) correspondto the pressure tap pairs 204. The valves 206A/206B are received invalve seats 208 when the valves are closed. Pressure relief taps 209 areprovided and wherein seat pressure relief taps 210 are coupled viapressure relief lines 212. Flow ports 214 act as the input ports for thesea water and are in fluid communication with a correspondingfilter-anchor unit 20, 22 or 24. Arrows 112 indicate the correspondingpiston motion direction while arrows 114 indicate the pressure-forcedirection. Arrows 216 indicate the sea water flow direction. Thehigh-pressure sea water feed flow line is indicated by 218 while thelow-pressure intake flow line is indicated by 220. A high pressuremanifold 222 takes the high-pressure sea water flow via path 224 to thereverse osmosis membrane 50.

In operation, the piston/rod assembly 102A/102C is excited by analternating energy source, namely, the water waves. The piston/rodassembly 102A/102C travels in alternating directions over the periodassociated with the water wave in the piston housing 102B. The motionscreate alternating pressures in the taps 104/204 due to the alternatingpiston-rod assembly motions 112. The alternating pressures aretransmitted through the control pressure lines 106, producingalternating pressure forces with directions shown as 114. The piston-rodassembly motions 112 cause the sea water in the pump 100 to bealternatively expelled at high pressure and refilled at low pressurethrough the intake/exhaust taps 108. The alternating flows through thetaps 108 are transmitted through the intake/exhaust lines 110. Thepressure forces 114 in the control pressure lines 106 alternately causethe cone-head valves 206A and 206B to open and close. The cone-head ofthe valves mate with the conical valve seats 208 when the valve isclosed. When the valve is to be opened by the pressure force 114, seawater is passed into the seat 208 through the seat pressure relief tap210 which is partially supplied by the pressure relief tap 209. The taps209 and 210 are interconnected by the pressure relief lines 212. Theresulting flows in the sea water flow ports 214 are in the directionsindicated by 220. In particular, the high pressure flow in the highpressure feed flow lines 218 travel in the direction 216. The lowpressure flow in the low pressure intake flow lines 220 in the direction221 come from the corresponding filter-anchor unit 20, 22 or 24. Thehigh pressure flow components through flow lines 218 are combined in amanifold 224 and this combined flow 226 is supplied to the reverseosmosis membrane 58.

While the invention has been described in detail and with reference tospecific embodiments thereof, it will be apparent to one skilled in theart that various changes and modifications can be made therein withoutdeparting from the spirit and scope thereof.

What is claimed is:
 1. A system for producing potable water comprising:(a) an articulated barge system for floating on a body of salt waterhaving waves, the barge system including a desalination system toproduce potable water from filtered salt water, the barge system beingarranged for converting energy of the waves into energy to pump thefiltered salt water to the desalination system, the desalination systemincluding a reverse osmosis membrane, the reverse osmosis membrane beingarranged to be self-cleaned by the action of the waves on the bargesystem; and (b) at least one filter-anchor, the at least onefilter-anchor being arranged for placement on the floor of the body ofsalt water and comprising a filter housing and a filter, the filterhousing having an interior chamber, at least one inlet, at least oneoutlet, and a filter located within the filter housing, the at least oneinlet being arranged for providing salt water to the filter, the filterbeing adapted to filter the salt water to produce filtered salt water,the outlet being coupled to the desalination system, whereupon the saltwater can be drawn into the filter and filtered to produce the filteredwater which can be pumped from the outlet to the desalination system bythe energy of the waves, said filter housing comprising a bargestructure that permits said filter housing to be towed to a sea waterlocation.
 2. The system for producing potable water of claim 1 whereinthe filter is a sand filter comprising clean, washed, coarse sand. 3.The system for producing potable water of claim 2, wherein the area ofthe at least one inlet provides a surface intake velocity of less than0.5 feet per second to restrict incursion of fish larva and macro ormicro vertebrae into the sand filter.
 4. The system for producingpotable water of claim 2, wherein the sand filter comprises a porous bagarranged for holding the sand in the interior chamber.
 5. The system forproducing potable water of claim 1, wherein the filter-anchor, isfloatable and towable to a deployment site in the body of salt water. 6.The system for producing potable water of claim 1, wherein the filterhousing comprises hatches to enable the submersion of the filter housingvia flooding of the interior chamber and controlled sinking of thefilter-anchor to the floor of the body of salt water.
 7. The system forproducing potable water of claim 6, wherein the hatches are closable andwherein the filter-anchor is arranged to be floated from the floor ofthe body of salt water by closure of the hatches and introduction of airinto the filter-anchor.
 8. The system for producing potable water ofclaim 1, wherein the filter housing comprises hatches to enable thesubmersion of the filter housing via flooding of the interior chamberand controlled sinking of the filter-anchor to the floor of the body ofsalt water.
 9. The system for producing potable water of claim 8,wherein the hatches are closable and wherein the filter-anchor isarranged to be floated from the floor of the body of salt water byclosure of the hatches and introduction of air into the filter-anchor.10. The system of claim 1 wherein the articulated barge system comprisesat least two barges which are hinged together and having at least onepump straddling the at least two barges and operative to pump thefiltered salt water to the reverse osmosis membrane in response to theaction of the waves on the barges.
 11. The system of claim 10 whereinthe at least one pump comprises a horizontal bi-directional linear pump.12. The system of claim 11 additionally comprising a flow rectifiercoupled to said horizontal bi-directional linear pump to produce aunidirectional water flow of the filtered water and deliver theunidirectional flow of filtered water to the reverse osmosis membrane.13. A method of producing potable water comprising: (a) floating anarticulated barge system on a body of salt water having waves, the bargesystem including a desalination system to produce potable water fromfiltered salt water, the desalination system including a reverse osmosismembrane; (b) towing at least one filter-anchor having a housingcomprising a barge structure on a surface of the body of salt water anddisposing said at least one filter-anchor on the floor of the body ofsalt water, the filter anchor comprises a filter housing and a filter,the filter housing having an interior chamber, at least one inlet, atleast one outlet, and a filter located within the filter housing, the atleast one inlet being arranged for providing salt water to the filter,the filter being adapted to filter the salt water to produce filteredsalt water; (c) coupling the outlet to the desalination system; and (d)utilizing the barge system to convert the energy of the waves intoenergy to pump the filtered salt water to the desalination system,whereupon the filtered salt water is converted to potable waterutilizing the reverse osmosis membrane, the reverse osmosis membranebeing self-cleaned by the action of the waves on the barge system. 14.The method of producing potable water of claim 13 wherein the sea waterprovided by the at least one inlet to the filter is at an intakevelocity of less than 0.5 feet per second to restrict incursion of fishlarva and macro or micro vertebrae.
 15. The method of producing potablewater of claim 14 wherein the filter is a sand filter, which comprises aporous bag and sand, the porous bag being arranged for holding the sandin the interior chamber.
 16. The method of producing potable water ofclaim 13 additionally comprising providing a mooring buoy for the atleast one filter-anchor.
 17. The method of producing potable water ofclaim 13 wherein the filter is a sand filter, which comprises a porousbag and sand, the porous bag being arranged for holding the sand in theinterior chamber.
 18. The method of producing potable water of claim 13,wherein the filter housing comprises hatches and wherein the hatches areopened to enable the submersion of the filter housing via flooding ofthe interior chamber and controlled sinking of the filter-anchor to thefloor of the body of salt water.
 19. The method of producing potablewater of claim 18, wherein the hatches are closable and wherein thefilter-anchor is floated from the floor of the body of salt water byclosure of the hatches and introduction of air into the filter-anchor.20. The method of producing potable water of claim 13 wherein thearticulated barge system comprises at least two barges which are hingedtogether and have at least one pump straddling the at least two barges,the at least one pump being operative to pump the filtered salt water tothe reverse osmosis membrane in response to the action of the waves onthe barges.
 21. The method of producing potable water of claim 20wherein the at least one pump comprises a horizontal bi-directionallinear pump.
 22. The method of claim 21 wherein the articulated bargesystem additionally comprises a flow rectifier coupled to saidhorizontal bi-directional linear pump to produce a unidirectional waterflow of the filtered water and deliver the unidirectional flow offiltered water to the reverse osmosis membrane.